Shockwave valvuloplasty catheter system

ABSTRACT

A valvuloplasty system comprises a balloon adapted to be placed adjacent leaflets of a valve. The balloon is inflatable with a liquid. The system further includes a shock wave generator within the balloon that produces shock waves. The shock waves propagate through the liquid and impinge upon the valve to decalcify and open the valve.

CLAIM OF PRIORITY

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/111,600, filed Nov. 5, 2008, which applicationis incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Aortic calcification, also called aortic sclerosis, is a buildup ofcalcium deposits on the aortic valve in the heart. This often results ina heart murmur, which can easily be heard with a stethoscope over theheart. However, aortic calcification usually doesn't significantlyaffect the function of the aortic valve.

In some cases, though, the calcium deposits thicken and cause narrowingat the opening of the aortic valve. This impairs blood flow through thevalve, causing chest pain or a heart attack. Doctors refer to suchnarrowing as aortic stenosis.

Aortic calcification typically affects older adults. But when it occursin younger adults, it's often associated with an aortic valve defectthat is present at birth (congenital) or with other illnesses such askidney failure. An ultrasound of the heart (echocardiogram) candetermine the severity of aortic calcification and also check for otherpossible causes of a heart murmur.

At present there is no specific treatment for aortic calcification.General treatment includes the monitoring for further developments ofheart disease. Cholesterol levels are also checked to determine the needfor medications to lower cholesterol in the hope to prevent progressionof aortic calcification. If the valve becomes severely narrowed, aorticvalve replacement surgery may be necessary.

The aortic valve area can be opened or enlarged with a balloon catheter(balloon valvuloplasty) which is introduced in much the same way as incardiac catheterization. With balloon valvuloplasty, the aortic valvearea typically increases slightly. Patients with critical aorticstenosis can therefore experience temporary improvement with thisprocedure. Unfortunately, most of these valves narrow over a six to 18month period. Therefore, balloon valvuloplasty is useful as a short-termmeasure to temporarily relieve symptoms in patients who are notcandidates for aortic valve replacement. Patients who require urgentnoncardiac surgery, such as a hip replacement, may benefit from aorticvalvuloplasty prior to surgery. Valvuloplasty improves heart functionand the chances of surviving non-cardiac surgery. Aortic valvuloplastycan also be useful as a bridge to aortic valve replacement in theelderly patient with poorly functioning ventricular muscle. Balloonvalvuloplasty may temporarily improve ventricular muscle function, andthus improve surgical survival. Those who respond to valvuloplasty withimprovement in ventricular function can be expected to benefit even morefrom aortic valve replacement. Aortic valvuloplasty in these high riskelderly patients has a similar mortality (5%) and serious complicationrate (5%) as aortic valve replacement in surgical candidates.

The present invention provides an alternative treatment system forstenotic or calcified aortic valves. As will be seen subsequently, theembodiments described herein provide a more tolerable treatment foraortic stenosis and calcified aortic valves than the currently performedaortic valve replacement. The invention also provides a more effectivetreatment than current valvuloplasty therapy.

SUMMARY OF THE INVENTION

In one embodiment, a valvuloplasty system comprises a balloon adapted tobe placed adjacent leaflets of a valve, the balloon being inflatablewith a liquid, and a shock wave generator within the balloon thatproduces shock waves that propagate through the liquid for impingingupon the valve. The balloon may be adapted to be placed on oppositesides of the valve leaflets or within the valve annulus.

The system may further comprise an elongated tube. The balloon may be atthe distal end of the elongated tube.

The balloon may include a first balloon chamber and a second balloonchamber. The first and second balloon chambers may be longitudinallyspaced from each other.

The elongated tube may include a lumen. The first and second balloonchambers are in fluid communication with the elongated tube lumen.

The shock wave generator may comprise a first shock wave source withinthe first balloon chamber and a second shock wave source within thesecond balloon chamber. The first and second shock wave sources maycomprise a first electrical arc generator and a second electrical arcgenerator. The electrical arc generators may comprise at least oneelectrode adapted for connection to a voltage pulse generator. Each ofthe electrical arc generators may comprise an electrode pair adapted forconnection to a voltage pulse generator. Each of the electrode pairs maycomprise a pair of coaxially arranged electrodes.

They may further comprise a high voltage catheter including the firstand second electrical arc generators. The first and second electricalarc generators may be longitudinally spaced from each other for beingreceived within the first and second balloon chambers, respectively.

As mentioned above, the balloon may be adapted to be placed within thevalve annulus. To that end, the balloon may have a reduced diameterportion adapted to be received within the valve annulus.

The balloon may be formed of a compliant material.

Alternatively, the balloon may be formed of a non-compliant material.

According to another embodiment, a catheter system comprises anelongated carrier and a balloon carried by the elongated carrier. Theballoon is arranged to receive a fluid therein that inflates theballoon. The system further includes at least one arc generatorincluding at least one pair of coaxially arranged electrodes within theballoon that forms a mechanical shock wave within the balloon.

The system may further include a cable comprising a center conductor andan outer conductive shield insulated from the inner conductor. A firstone of the coaxially arranged electrodes may be at least in part formedby the center conductor of the cable, and a second one of the coaxiallyarranged electrodes may be at least in part formed by the outerconductive shield of the cable.

According to a further embodiment, a valvuloplasty method for treating avalve having leaflets and an annulus comprises placing a balloonadjacent to the leaflets of the valve, inflating the balloon with aliquid, and producing shock waves within the balloon that propagatethrough the liquid for impinging upon the valve leaflets and the valveannulus.

The placing steps may be performed by placing the balloon on oppositesides of the valve leaflets. Alternatively the placing step may beperformed by placing the balloon within the valve annulus.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The variousdescribed embodiments of the invention, together with representativefeatures and advantages thereof, may best be understood by makingreference to the following description taken in conjunction with theaccompanying drawings, in the several figures of which like referencenumerals identify identical elements, and wherein:

FIG. 1 is a cut away view of the left ventricle, the aorta, and theaortic valve of a heart showing a reduced aortic valve open area andthickened valve leaflets due to calcium and fibrotic tissue;

FIG. 2 is a cut away view of the aortic valve of a heart with atreatment balloon placed on both sides of the aortic valve leaflets,according to an embodiment of the present invention;

FIG. 3 is a schematic view of a dual shockwave balloon embodying theinvention attached to a high voltage power supply; and

FIG. 4 is a cut away view of a heart showing an alternate valvuloplastyshock wave balloon according to a further embodiment and aspects of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, it is a cut away view of the left ventricle 12,the aorta 14, and the aortic valve 16 of a heart 10 with a stenotic andcalcified aortic valve 16. Here more particularly, it may be seen thatthe opening 17 of the stenotic and calcified aortic valve 16 isrestricted in size and that the valve leaflets 18 are thickened withcalcium deposits and fibrotic tissue. The thickened leaflets 18 andsmaller valve opening 17 restrict blood flow from the heart creatingexcess work for the heart 10 and poor cardiac output. As previouslymentioned, current treatment includes replacement of the valve orattempts too stretch the valve annulus with a balloon.

FIG. 2 is a cut away view of the aortic valve 16 with a treatmentballoon 22 placed on both sides of the aortic valve leaflets 18. Theballoon 22 may be formed from a compliant or a non-compliant material.The balloon, as seen in FIG. 2, is at the distal end of an elongatedtube 23. The treatment balloon 22 has two longitudinally spaced chambers24 and 26 that share a common inflation lumen 25 of the tube 23.Alternatively the balloon chambers 24 and 26 may not share the sameinflation fluid path. The chambers 24 and 26 are longitudinally spacedsuch that chamber 24 is positioned on one side of the aortic valveleaflets 18 and chamber 26 is positioned on the other side of the aorticvalve leaflets 18. The chambers 24 and 26 are inflated withsaline/contrast mixture, for example. Each chamber 24 and 26 may containan electrode (as shall be seen subsequently) that can produce electricalarcs to deliver timed shock waves. The shock waves can be synchronizedto concurrently impinge upon both sides of the leaflets 18 to maximizethe effectiveness of breaking calcium deposits. Such shock waves may begenerated and also synchronized to the R wave of the heart 10 in amanner as described for example in copending application No. 61/061,170filed on Jun. 13, 2008, which application is incorporated herein in itsentirety.

FIG. 3 is a schematic view of a valvuloplasty system 11 embodying thepresent invention. The system 11 includes the dual shockwave balloon 22.The balloon 22 has received a high voltage catheter 32 that is connectedto a high voltage power supply 30. The schematic representation showsthe positioning of the balloon chambers 24 and 26 above and below theleaflets 18 of the aortic valve 16. As previously described, shock waveswill impinge upon opposite sides of the leaflets 18 to more effectivelybreak calcium deposits in the valve leaflets 18. The annulus will alsobe treated in this arrangement. To that end, the high voltage catheter32 includes electrode pairs 34 and 36 that are coaxially arrangedelectrodes placed in chambers 24 and 26 respectively of the balloon 22.More specifically, electrode pair 34 is at the distal end of a firstcable and comprises a center conductor 33 and an outer conductive shield35. Similarly, electrode pair 34 is at the distal end of a second cableand comprises a center conductor 37 and an outer conductive shield 39.High voltage pulses from power supply 30 are applied to the electrodepairs 34 and 36 in a manner as described in the aforementionedapplication Ser. No. 61/061,170 to create shockwaves within the fluidwithin the chambers 24 and 26 of the balloon 22. The shock waves impingeupon the valve leaflets 18 and the valve annulus to cause the break upof calcium deposits and fibrotic tissue on the valve leaflets 18 andannulus to open the aortic valve 16.

FIG. 4 shows an alternate valvuloplasty shock wave balloon 42 at thedistal end of an elongated tube 43. The balloon 42 is placed in theannulus of the aortic valve 16. To that end, the balloon 42 has areduced diameter portion 45 for being received within the valve annulus.The balloon 42 has a high voltage catheter 44 therein that terminates inan electrode pair 46. As in the previous embodiment, the electrode pair46 may comprise a pair of coaxially arranged electrodes where a centerconductor may form at least a part of one electrode and at an outerconductive shield may form at least a part of the other electrode. Thecatheter 44 and its electrode pair 46 provide shock waves as previouslydescribed. Such an arrangement will decalcify the leaflets 18. This notonly will decalcify the leaflets 18, but will also soften the aorticvalve annulus and expand its diameter. Hence, the balloon 42 providesthe added advantage of exerting expansion pressure directly to theannulus of the valve to remodel the annulus diameter.

While particular embodiments of the present invention have been shownand described, modifications may be made, and it is therefore intendedto cover all such changes and modifications which fall within the truespirit and scope of the invention.

What is claimed is:
 1. An intravascular valvuloplasty system fortreating a valve having leaflets and an annulus by breaking calciumdeposits on the leaflets and annulus of the valve, each leafletconnected to a wall and having a concave region, comprising: an elongatebody; a balloon being inflatable with a liquid via an inflation lumen ofthe elongate body, wherein the inflated balloon has a portion shaped tofit within the concave region of a leaflet and between the leaflet andthe wall; and a shock wave generator having a pair of electrodes locatedwithin the balloon that produces a plurality of high voltage pulsesacross the electrodes to generate electric arcs that create shock wavesthat propagate through the liquid for impinging upon the valve, theballoon being configured to remain intact as the shock waves areproduced by the shock wave generator.
 2. The system of claim 1, whereinthe balloon is at the distal end of the elongate body.
 3. The system ofclaim 1, wherein the shock wave generator has a voltage pulse generatorand said pair of electrodes are adapted for connection to the voltagepulse generator.
 4. The system of claim 1, wherein the balloon is formedof a compliant material.
 5. The system of claim 1, wherein the balloonis formed of a non-compliant material.
 6. The system of claim 1, whereinthe pair of electrodes include one pair of coaxially arranged electrodeswithin the balloon.
 7. The system of claim 6, further including a cablecomprising a center conductor and an outer conductive shield insulatedfrom the inner conductor, wherein a first one of the coaxially arrangedelectrodes is at least in part formed by the center conductor of thecable, and wherein a second one of the coaxially arranged electrodes isat least in part formed by the outer conductive shield of the cable. 8.The system of claim 1, wherein the shock wave generator within theballoon produces rapidly expanding and collapsing bubbles in the liquidwithin the balloon that form a plurality of shock waves that propagatethrough the liquid for impinging upon the valve.
 9. The system of claim1, wherein the balloon is a single layer balloon.
 10. The system ofclaim 1, wherein the pair of electrodes comprises an inner electrode andan outer electrode shield that surrounds the inner electrode.